Electrical apparatus



July 3; 192a. 1,675,567 I L. L. LocKRow ELECTRICAL APPARATUS Filed Sept. 14, 1921s Amplifi'cr Detect am A A A 1) D Patented July 3, 1928.

UNITED STATES LAURICE'L. LOCKROW, OF EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY,

PORATION OF PENNSYLVANIA.

F SWISSVALE, PENNSYLVANIA, A COR- ELEGTRICAL APPARATUS.

Application filed September 14, 1926. Serial No. 135,398.

My invention relates to electrical appa- ,Iatus, and particularly to apparatus of the type comprising a load supplied with energy from a source of pulsating current.

One object of my invention is the provision, in apparatus of the type described, of means for smoothing out the pulsations in the current supplied to the load.

I will describe one form of apparatus embodying my invention, and will then. point out the novel features thereof in claims.

The acompanying drawing is a diagrammatic view illustrating one form of electrical apparatus embodying my invention.

Referring to the drawing, the apparatus comprises a source of pulsating current which is here shown as a rectifier R supplied with energy from the secondary b of a transformer 'l. The primary 1 of this transformer is supplied with alternating current from a suitable source here shown as an alternator X.

The rectifier R comprises a plurality of asymmetrical units which may be of the copper oxide type described andillustrated in an application for Letters Patent of the United b'tates, Serial No. 1111, filed J anuary 7, 1925, by Lars O. Grondahl' for unidirectional current carrying devices. These asymmetrical units ofl'er considerably higher resistance to current flowing through them in one direction than to currentfiowing in the opposite direction. The direction of lesser resistance is indicated by the arrows.

The rectifier Rsupplies pulsating current to 'aload which is here illustrated as the filaments 5 and 12 of a plurality of electron tubes A A A, and D D respectively, such as are used in radio receiving circuits. In

serieswith each filament 5 is a resistor 4, and

connected in series with each filament 12 is a resistor 11. These filaments are connected across the treminals l4 and 15 of the rectifier B through two reactors 6 and 13. During one half cycle, current is supplied from the secondary S of the transformer T, through wire 1, unit 10, reactor 6, multiple connected filaments 5 and resistors 4, wire 3, unit 9, and wire 8 back to the secondary S. Current is also'supplied during this half-cycle through the reactor 13,- and filaments 12 and resistors 11 in multiple. During the opposite halfcycle current issupplie .fromthe secondary S of transformer T, through wire 8, unit 7, reactor filaments 5 and resistors 4 in multiple, wire 3, unit 2 and wire 1 back to secondary During the second half cycle current is also supplied through the reactor 121}, and filaments l2 and resistors 11 in multip e.

The current supplied from the rectifier R normally pulsates in a manner which would tend to produce disturbances in the plate current of the amplifier tubes A A and A and also in the plate current of detector tubes .D and 1). In order to smooth out these pulsations the reactors 6 and 13 are provided. The reactor 6 which is associated with the amplifier tubes A A and A has a low direct current resistance because these tubes require considerable current, but due to the connections of the filaments 5 and the resisters 4 in multiple, the pulsations in the rectified current are smoothed out, the'voltage induced in the reactor 6 when the current is decreasing being in such direction as to oppose the decrease in current. The filaments 5 and resistors being non-inductive, cooperate with the reactor 6 to form a ladder filter which may be proportioned to oppose the passage of the alternating component of the rectified current. The reactor 13 co-operates with the detector tubes D and D in a similar manner but this reactor has a high ohmic'resistance because the detector tubes require much less current than the amplifier' tubes. ,This reactor may be propor- .tioned with respect to filaments 12 and resistors 11 to effectively smooth out the pulsations in the current supplied to the filaments 12. By suitably proportioning the reactors 6 and 13 the pulsations in the rectified current may be so reduced as to eliminate undesirable disturbances in the plate circuits oi the detector tubes D and D.

It will now be seen that I have provided a. circuit which will reduce the disturbances in the plate circuits of electron tubes having their filaments supplied with alternating current by filtering out the undesirable components and that this circult requlres, for performing the filtering operation, very little extra apparatus over that "WlllCll is normally required without the filter.

Although I have herein shown and described only .oneform of electrical apparatus embodyingmy invention, it is understood that various changes and modifications may be made therein, within the scope of 2 3. In combination, a

the appended claims, without departing from the spirit and scope of my invention.

v Having thus described my invention, what I claim is:

arranged to co-operate with the reactors to form a ladder filter. L

2. In comblnation, a source of uni-directional pulsating current, a plurality of electron tubes having their filaments connected 1n multiple, a resistor in series witheach filament,-.and a reactor in series with the source andco-operati'ng with the resistors to form a ladder filter.

source of pulsating current, a plurality of electron tube amplifiers having their filaments connected in multlple with one another across the source, a resistor in series with each filament, a low resistance reactor connected between the source and the filaments ofthe amplifiers and co-operating with said filaments and resistorszto form a ladder filter, a plurality of electron tube detectors also having their filaments connected in multiple with one another across the source, a resistor in series with each detector tube filament, and a high resistance reactor in series with the source and with the low resistance reactor and connected between the amplifier and detector tubes and co-operating with each detector tube filament and its associated resistor to form a ladder filter. I

In testimony whereof I aifix my signature.

LAURICE L; LOCKROW. 

